var MyQueue = function () {
  this.stack1 = [];
  this.stack2 = [];
};

MyQueue.prototype.push = function (x) {
  this.stack1.push(x);
};

MyQueue.prototype.pop = function () {
  if (this.stack2.length === 0) {
    while (this.stack1.length) {
      this.stack2.push(this.stack1.pop());
    }
  }
  return this.stack2.pop();
};

MyQueue.prototype.peek = function () {
  // if (this.stack2.length === 0) {
  //   while (this.stack1.length) {
  //     this.stack2.push(this.stack1.pop());
  //   }
  // }

  const top = this.pop();
  this.stack2.push(top);
  return top;
};

MyQueue.prototype.empty = function () {
  return !this.stack1.length && !this.stack2.length;
};
